High solids copolymer dispersion from a latex and its use in caulks, sealants and adhesives

ABSTRACT

A method for polymerizing predominantly one or more acrylate and/or vinyl acetate monomers in the presence of a latex results in high solids dispersions of polymer particles with lower viscosities than traditionally observed. A significant wt. % of added monomers can be present in large particles, having nonspherical shapes. Some of the original latex particles are retained during the polymerization and these increase the solids content and lower the viscosity by packing in the interstices between large particles. The total polymer solids content can easily be varied from 70 to 92 or more wt. % which are higher than achieved in any previously reported aqueous polymerizations. The viscosities at very high solids contents become paste-like but the materials still are stable to storage and further handling without breaking the dispersion into an agglomerated polymer portion and released water. The dispersions are useful to form sealants, membranes, etc., either with or without other additives. A preferred use is as an acrylate water-based caulking compound where the high solids and thixotropy of the dispersion allows for formation of a water-based caulk with low shrinkage.

This application is a continuation-in-part of U.S. application Ser. No.08/690,288, filed Jul. 26, 1996, for "High Solids Copolymer DispersionFrom a Latex and its Use in Sealants," and now U.S. Pat. No. 5,744,544and which is a continuation-in-part of U.S. application Ser. No.08/321,288, filed Oct. 11, 1994, for "High Solids Copolymer DispersionFrom a Latex and its Use in Sealants," which issued as U.S. Pat. No.5,541,253 on Jul. 30, 1996.

FIELD OF INVENTION

This invention relates to high solids, free radical polymerizations ofacrylate and/or vinyl acetate monomers in a latex resulting in highsolids (desirably greater than 50 wt. %, preferably 70-95 wt. %)dispersion of polymer particles. The monomer composition polymerized inthe presence of the latex need not be similar to the composition of themonomers used to make the latex and may be chosen to modify theproperties of dried films from the dispersion. The high solids makes thematerial economical to ship or store and when formulated into a caulkingsealant results in a sealant with low modulus, high elongation and lowshrinkage.

BACKGROUND

Traditionally, higher performance sealants and caulks have beenformulated using solvent based polymer systems such as silicone andpolyurethane polymers as the binder for the sealant formulation. Thesesolvent based types of sealant formulations generally yield sealantswith good application properties (thixotropy and viscosity) and in thecured form typically have the elastomeric properties and adhesionrequired for a high performance sealant or caulking material. However,in recent years, with increasing government regulation and heightenedconsumer awareness, the manufacturers of solvent based sealants arecoming under increasing pressure to reduce the VOC (volatile organiccontent) of their product (i.e. organic solvent content).

Dispersions of polymer particles in water have been used extensively inwater-based sealants such as coatings and caulking. Their low viscosity,low volatile organic emissions, and ease of application have beenfavorable factors for their use. However, irrespective of the polymerparticle sizes there has been a barrier at from 40-65% solids (dependingon emulsifier type and other conditions) above which dispersions ofpolymer particles are difficult to prepare. Therefore high solidssealants were made by adding fillers. The fillers dilute the polymer inthe final application lowering elongation and increasing modulus.Polymers having low Tg values (such as below 0° C.) which areparticularly useful in formulating sealants and caulks requiring lowtemperature flexibility are sticky.

One example of high solids polymerization is European Patent PublicationNo. 0 515 719 A1, which discloses a self-adhering acrylate copolymer,which can be used for the production of self-adhering surface layerformulations. This acrylate copolymer is produced by a combinedsuspension and emulsion polymerization. The solids content recited are30-70 wt. % and the examples show 65 wt. % solids.

An article by Do Ik Lee in the Journal of Paint Technology, Vol. 42, No.550 (1970) pp 579-587 discusses the packing of binary mixtures ofspheres.

U.S. Pat. No. 4,130,523 to Hoy and Peterson discloses nearly 70 volume %solids. Their latex particles are desirably no larger than 1.5 micronsin diameter.

It is the object of the current application to polymerize in thepresence of a preformed latex additional monomers creating a highsolids, low viscosity, thixotropic product especially useful in coatingsand sealants.

SUMMARY OF THE INVENTION

It has been found that a latex dispersion of latex polymer particles,when used as the medium for a further polymerization, can result in highsolids content (such as 70-95 wt. %) polymer particle dispersions withlower viscosities than achieved with traditional polymerization. Theresulting dispersions show bimodal or multimodal particle sizedistributions with particle diameters ranging from around 0.05 to 100microns. The resulting broad particle size distribution, and good mixingduring polymerization are believed to be major factors allowing highsolids contents to be achieved.

Upon removal of shear, the polymer particle dispersions thicken but arecapable of being liquified. The large particles (above 4 μm) when formedare typically nonspherical, desirably having an average aspect ratiobetween the largest and smallest diameter of each particle of at least1.5.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an acrylate dispersion made similarly to Examples 1-3 at amagnification of about 675×. Table VI shows the specific pH and weightpercent solids of A-K. The breadth of the particle size distribution andvariation in shape of the particles are easily seen by this microscopicexamination technique which sandwiches a drop of the polymer dispersionbetween two microscope slides.

DETAILED DESCRIPTION OF THE INVENTION

High solids polymer particle dispersions are created by polymerizingmonomers in the presence of a latex (i.e., using the latex as thepolymerization medium). A latex, as specified herein, is defined as adispersion of small polymer particles (i.e. weight average particlediameters of less than 2 μm) in a water-based media. The latex serves asa primary source of the smaller particles in the final dispersion ofparticles. The latex also serves as the water-based media for furtherpolymerization

Also, mixtures of latexes can be used as the starting material givingeven more flexibility to the composition and properties of the finaldispersion and films or caulks derived from the dispersion. Suchdispersions are usually thixotropic, especially at solids above 75percent by weight. The thixotropy enhances the uses of the polymer insealant applications where the material is applied with a low viscosityat a high shear rate. The material can have a high viscosity and thusresist flow (such as runoff) under low shear conditions. Preferredpolymers for the process and sealants include poly-(acrylate),poly(vinyl acetate), and copolymers or combinations thereof.

The monomers polymerized in the presence of the latex are desirablyadded over a period of time such as by metering them into the latex ormetering the latex and monomers simultaneously. The preferred monomershave low water solubilities (i.e., less than 5 wt. % soluble in water)such that dispersed monomer droplets are formed. These droplets can beconverted into polymer particles by polymerization. The large polymerparticles ultimately created in this polymerization, vary from about 2to about 200 μm in diameter. The solids content of the dispersion ofpolymer particles is desirably at least 50, 60, 65, 75, 77 or 80 wt. %.Desired ranges are also from 70 to 95 wt. % or 75 to 85, 88, 90 or 92wt. % of the dispersions.

The technique of adding monomer to a preformed latex can be conductedwith any acrylate or vinyl acetate based latex. The viscosity of thedispersion will generally be lower than similar dispersions made byother sequences of emulsion and suspension polymerization. When thestarting latex has from 40 to 68% solids, the resulting dispersion ofpolymer particles can have greater than 70 wt. % or preferably 75 to 92wt. % solids.

The starting latexes with from 40 to 68 weight percent solids vary fromstandard emulsion polymerized latexes because they are often bimodal ormultimodal. This is because wide particle size distributions ormultimodal distributions are known to have lower (processable)viscosities at high solid levels. The higher solids starting latexes canbe readily achieved by shifting the diameter of one or more modes orincreasing or decreasing the amount of particles of one or more particlediameter. The technology to create broad or multimodal distributions isdisclosed in European Patent Publication No. 0 515 719 Al and U.S. Pat.No. 4,130,523, both further identified in the Background of thisapplication and hereby incorporated by reference. A review articleentitled "Concentrated Colloidal Dispersions", Faraday Discussions ofthe Chemical Society, No. 76, published by the Royal Society ofChemistry, London 1983 is hereby incorporated by reference and, furtherdescribes various ways to prepare high solids latexes.

Commercially available high solids latexes are available under the nameRhoplex™ 2620 from Rohm and Haas at 62 weight percent solids being anacrylate latex; under the designation Carbobond™ XPD 2254 available atabout 67 percent solids from The BFGoodrich Company, Brecksville, Ohio,which was used in Examples 1-4; and under the name Acronal V275™available from BASF at 65 weight percent solids. The Acronal V275™varies from the other two latexes in having a few weight percent ofacrylonitrile included in the polymer.

During the polymerization in the presence of the latex, new smallparticles (less than 0.5 μm and sometimes less than 0.10 μm in diameter)have been observed initially. At a certain solids content (depending onmany factors such as the emulsifiers, monomers of the latex, andmonomers added during the polymerization) the relative number of newsmall particles appears to decrease (presumably due to agglomeration)and larger particles (greater than 2 μm diameter) are observed ingreater numbers. The agglomeration of small particles into largerparticles seems to occur in a controlled manner without the formation ofcoagulum (which would be expected in typical polymer dispersions inwater when agglomeration occurs). Although the above particles are oftenseen the method of polymerization does not require their presence. Inexamples 1 and 2, the larger particles are in the 2 to 4 μm diameterrange while in the later Examples the particles exist at modes indiameter from 2 to 4 and 8 to 30 μm in diameter. Thus, Examples 1 and 2show bimodal distributions while Examples 3 and 4 show trimodaldistributions of particle diameters.

These high solids polymer dispersions are particularly useful forsealants, especially caulking-type water-based sealants. The evaporationof water from conventional low solids water-based caulks during curingcauses extensive undesirable shrinkage. The shrinkage in water-basedcaulking results in residual stresses and strains which may cause thecaulking to pull away from one or more of its bonded surfaces. Bydecreasing the relative amount of water in caulking formulations one candecrease the maximum water loss and maximum amount of shrinkage. When acaulking formulation starts with a higher solids polymer dispersion, thefinal caulk can achieve still higher solids content with the addition ofnonvolatile fillers. Alternatively the caulking formulation may achieveequivalent solids content with less fillers. This usually results in acaulking formulation with higher elongation, lower modulus, andincreased adhesion to the substrate.

The viscosity of a caulk increases with the addition of particulatesolids to low solids polymer dispersions. The addition of large amountsof particulate solids to a water based caulking formulation greatlyincreases the modulus and decreases the ultimate elongation at break ofthe cured formulated caulking compound and therefore reduces theperformance of the caulking material.

The viscosities of these dispersions vary with solids content but aregenerally lower than those produced by other aqueous polymerizations.For a 75 wt. % or more solids dispersion the viscosity is desirably lessthan 30,000 cps at 24° C., 20 rpm, with a cone and plate viscometer.More desirably the viscosity is less than 20,000 cps. At 70 to 80 wt. %solids the viscosity is desirably less than 10,000 cps under the samemeasuring conditions.

Preferred monomers for the latex and/or the polymerization in thepresence of the latex are one or more alkyl acrylates having 4 to 16 ordesirably 4 to 12 carbon atoms such as ethyl, butyl, and ethylhexylacrylate and/or vinyl acetate. Alkyl (alkyl)acrylates are included inthe general term the alkyl acrylates, although they tend to have higherglass transition temperatures. Preferably, the polymers in either orboth the latex polymer particles or the larger polymer particles have atleast 50, 70, 75, 80, or 90 wt. % of their repeat units derived from thealkyl acrylates or vinyl acetate and preferably just alkyl acrylates.Such acrylates are derived from the esterification of one or more(alkyl) acrylic acids, such as methacrylic acid and one or more alkylalcohols having 1 to 12 carbon atoms. Also preferred for the principalpolymer as specified above (i.e., at least 70, 80, or 90 wt. % thereof)is that it be a substantially non-crystalline polymer (e.g. elastomericor behaving as an elastomer at 20° C.) having a Tg of 0° C. or less andpreferably -20° C. or less. These type polymers when properly cured canhave reversible elongations of 200 percent or more and are thus calledelastomers.

Other monomers that can be used include the ethylenically unsaturatedmonomers. These include monomers having from 3 to 16 carbon atoms andoptionally one or more heteroatoms of O, N, Cl and/or F. These includethe conjugated dienes (preferably 4 to 8 carbon atoms); other monomershaving carboxylic acid or ester functionality such as di-n-butylmaleate; acrylic acid; maleic anhydride; isobutyl itaconate;acrylonitrile; (alkyl)acrylonitriles; acrylamides; and derivativesthereof; alpha-methylstyrene, styrene, vinyl chloride, vinylidenechloride, vinyl propionate and other higher esters of the vinyl acetatefamily having from 4 to 30 carbon atoms. Multifinctional monomerscapable of crosslinking such as diacrylates or divinylbenzene may alsobe used. Other monomers also include functionalized acrylates havingfrom 4 to 16 carbon atoms such as acrylates having pendant carbon-carbondouble bonds or pendant epoxy rings. These above listed monomers mayoptionally be present in the latex used as polymerization media. Thesemonomers are desirably present in complementary amounts to the acrylatesand vinyl acetate (i.e. 100%--the wt. % acrylates and/or vinyl acetate).

Desirably, the monomers used to form the larger particles include 10 wt.% or less, desirably 7 wt. % or less of the highly water solublemonomers (i.e., those with solubilities in water of 5 or 10 wt. % orgreater). Examples of the limited highly water soluble monomers includeolefinic monoacids having 3 to 10 carbon atoms, acrylic acid, olefinicdiacids having 4 to 12 carbon atoms, and acrylonitriles having 3 to 10carbon atoms.

The preferred media for the latex is water or blends thereof whichblends are substantially (i.e., 70, 80, 90 or more wt. %) water.Solvents may be used in small amounts in the blend such as alcohols,glycols, chlorinated alkyls, etc.

The emulsifiers (a term which includes surfactants) useful in the latexor the latex polymerization are the commercial anionic emulsifierscommonly used for emulsion polymerizations such as alkyl sulfonates orpolysulfonates; olefin or polyolefin sulfonates or polysulfonates; andcarboxylates or polycarboxylates made from alkyls, olefins, orpolyolefins. Other emulsifiers such as nonionic or cationic emulsifierscan be used, as can blends of anionic and nonionic emulsifiers.Polymeric emulsifiers, formed during the reaction or added separatelymay also be used. The nonionic and cationic emulsifiers are desirablyused in lesser amounts such as less than 50 wt. %, 30 wt. %, or 10 wt. %of the total emulsifiers at any time in the dispersion of polymerparticles. Desirably, the emulsifiers are less than 10 wt. % andpreferably less than 1 or 2 wt. % of the final dispersion of polymerparticles.

Any conventional chain transfer agents for emulsion, dispersion, orsuspension polymerization can be used. These additives function toreduce polymer branching and molecular weight, which serves to preventmacromolecular gel during polymerization.

The latex used as the medium for the polymerization of the additionalmonomers desirably has a pH from about 1 to 11 more desirably from 3 to9, and preferably from about 5 to 7. It is preferred that the pH beadjusted with alkali metal hydroxides selected from Na, Ca, K, and Li;or ammonia; or amines having up to 3 substituents with each substituenthaving up to 15 carbon atoms. Ammonia is the most preferred.

The initiators for the polymerization of emulsion-sized polymerparticles and/or larger polymer particles may be any of those known tothe prior art. The initiators for the polymerization may be any of thoseknown to the prior art for free radical polymerization in organicsolvents, in bulk, or in aqueous media such as emulsion or suspensionpolymerization. Preferred initiators include oil soluble azo and peroxythermal initiators typically used in solution polymerizations in organicsolvents such as, but not limited to, 2, 2' azobisisobutyronitrile, 2,2'-azobis (2, 4-dimethylvaleronitrile), 2, 2'-azobis (2methylbutyronitrile), di(2-ethylhexyl) peroxydicarbonate, tert-amylperoxyneodecanoate, hexylene glycol peroxy neoheptanoate. Water solublethermal initiators typically used in emulsion polymerization such as,but not limited to, ammonium persulfate can also be used successfully.Redox initiators such as, but not limited to, tert-butyl hydroperoxide,or cumene hydroperoxide with sodium formaldehyde sulfoxylate or sodiumbisulfite or potassium metabisulfite can also be used successfully . Oilsoluble redox initiators such as benzoyl peroxide with N,N-dimethyltoluidine can also be used successfully.

The dispersion of polymer particles desirably has two or more groups ofdispersed polymer particles resulting in a broad particle sizedistribution. One group is polymer particles of a weight averagediameter from about 0.05 to 0.7 μm and more desirably from 0.08 to 0.6μm. Another group is desirably from 0.7 to 4 μm and more desirably from1.0 to 3.5 or 4 μm. The particles between 0.05 and 0.7 μm and some ofthe particles between 0.7 and 4 μm will primarily be derived from thelatex and are desirably present from about 2 to about 20 wt. %, moredesirably from about at least 10 to 20 wt. % of the total polymerparticles. In the final dispersion of polymer particles, these particlesfrom the latex will be present (probably in fewer number) as one or moremodes in the particle size distribution. These modes in the particlesize distribution are desirably present at diameters of from 0.05 μm to0.6 μm or 0.7 μm and from 0.7 μm to 4 μm, and more desirably from 0.1 μmto 0.5 μm and 1.0 μm to 3.5 μm, and most preferably around 0.3 μm and2.0 μm. Thus at least one mode will be less than 1 μm and at least onemode will be greater than 1 μm. Another group of particles will bepresent having particle diameters greater than from 4 μm to 100 μm or200 μm. As these large particles (greater than 4 μm in diameter) arelater disclosed to be nonspherical the diameter values recited hereinare calculated average diameters for each particle reported by dynamiclight scattering particle size measurements. These particles will resultin a mode in the particle size distribution desirably from 4 μm to 100μm and preferably from 6 μm to 40 μm. Each of these particle size rangeswill have a weight mean particle size. Desirably, the weight meanparticle size of the large (greater than 4 μm) polymer particles will befrom 5 to 30 times the weight mean particle size of the small (4 μm orless) polymer particles. Desirably, for the higher solids polymerdispersions, at least 5, 10, 15, 60, or 70 wt. % of the polymer of thedispersion are these large particles having a diameter of at least 4 μmand more desirably between 4 μm and 100 μm. Desirably, at least 70, 80,or 90 wt. % or more of the particles in the dispersion fall into thecombined small and large size ranges specified.

The particle size distributions found in the polymer dispersions aredifferent than the normal particle size distributions created byemulsion or suspension polymerizations. In bimodal and multimodalparticle size distributions it is possible to have at least 30, 35 or 50weight percent of the particles having an average diameter greater than1 μm and more desirably between 1 and 4 μm with the high solids contentspreviously described. A preferred multimodal distribution is from 5 to30 weight percent of the particles having diameters between 0.05 and 0.7μm; 20 to 70 weight percent of the particles having diameters from 0.7to 4 μm; and 5 to 75 weight percent and more desirably 30 to 75 weightpercent having particle diameters from 4 to 100 μm.

The particle diameters referred to herein are those determined by lightscattering measurements. These correlate well with measurements bydiffusion and sedimentation, column chromatography, and examination inan electron microscope. When average sizes are referred to without abasis, weight average sizes are preferred. A mode in a particle sizedistribution is used to define a peak or maxima therein. When a mode isdefined as having particles therein, this means the mode is thepredominant diameter present in a peak of the particle sizedistribution.

The process of this disclosure is the formation of a stable dispersionof polymer particles, by polymerizing unsaturated monomers in apreformed latex. The additional monomer is added either in a batch, bymetered addition or added incrementally over a period of time. By thisprocess a substantial portion of the added monomers are convertedeventually into large polymer particles (such as from 2, 4, or 6 μm to200 μm). It is desirable to add the free radical initiator over a periodof time (e.g. during the polymerization), or to select free radicalinitiators that generate an effective level of free radicals over thecourse of the polymerization.

It is desirable that the monomers be added over a period of time (suchas metered in) as from about 1/2 hour to 24 hours, desirably from 1 hourto 10 hours, and preferably from 11/2 to 6 hours. It is also desirablethat the selected initiator and polymerization temperature are such thatmonomers are readily converted to polymer particles during the periodover which the monomers are added. Thus, the amount of unpolymerizedmonomers is minimized within the polymer dispersion and the reactionvessel during the polymerization by incremental or continuous additionof monomer and continuous polymerization of monomers to polymers.

Some of the original latex polymer particles may be lost due toagglomeration or coagulation during this process. However, a significantnumber of the smaller latex particles, e.g. 4 μm or less, are retainedduring this process. The presence of at least two substantiallydifferent diameter modes in the distribution of particle diameterswithin one dispersion of polymer particles is partially attributed withachieving solids contents above 70 wt. % in the form of flowable liquidsor pastes. Many of the particles above 4 μm formed by the process have anonspherical shape due to their method of formation. This results in anaverage aspect ratio for the particles above 4 μm in diameter, desirablyabove 1.5, and more preferably above 2. The average aspect ratio is theaverage from a group of particles of the quotient of the largestdiameter over the smallest diameter of each particle. These values areusually determined by examination of electron microscope photographs ofthe particles.

The latex used as the primary source of the polymerization media isdesirably a latex derived predominantly from one or more alkyl acrylateand/or vinyl acetate monomers. The other monomers previously describedfor use in the polymerization may also be present in the form ofpolymers or copolymers in the latex. Desirably, in one embodiment thepolymers of the latex have at least 50, 70, 80 or 90 wt. % of theirrepeat units derived from alkyl acrylates and/or vinyl acetate andpreferably from alkyl acrylates having from 4 to 16 carbon atoms. Thelatex desirably is an anionically stabilized latex. That means the latexis primarily stabilized by anionic emulsifiers (a term which includessurfactants). Desirably the latex polymers contain at least 0.05 wt. %repeat units from unsaturated mono and dicarboxylic acid monomers andmore desirably from 0.1 or 0.5 to 10 or 20 wt. %. Unsaturated carboxylicacid monomers include those having up to 12 carbon atoms. Such monomersinclude acrylic acid, methacrylic acid, itaconic acid, maleic acid andthe like. The latex media is desirably 20 to 70 wt. % solids and morepreferably 50 to 68 wt. % solids. The term solids refers throughout thespecification to the determination of the components which do notreadily volatilize within one hour at 105° C.

It is advantageous but not necessary to have two or more stirrers in thereaction vessel. The agitator of the reaction vessel most desirably isone capable of thoroughly mixing and homogenizing high viscosity highlythixotropic materials such as shown in the examples. Sufficient shear isdesirable to maintain the thixotropic material in a shear thinned(liquid) state. The nonspherical particles above 4 μm in diameter aretypically formed at higher solids where higher shear conditions exist.Thus a relationship between the mixing conditions and particlemorphology is suggested. The agitator is desirably designed to come inclose contact with the reactor walls and to thoroughly mix materialsinside the reactor. An anchor type mixing blade is desirable.

Optionally, no additional emulsifiers are added with the additionalmonomers. It is believed that some of the emulsifiers from the latex aredesorbed from the small particles and are adsorbed onto the monomerdroplets and large polymer particles. It is recognized that sufficientemulsifier must be present to stabilize the particles againstcatastrophic coagulation. Thus, if insufficient emulsifier is present inthe latex, additional emulsifier can be added during or after themonomer addition or prior to the addition of monomers.

The term thixotropic has been used to define the dispersion of polymerparticles. The thixotropic dispersion refers to a dispersion wherein themeasured viscosity decreases by a factor of from 5 to 1,000 when theshear rate (rpm) of the viscometer used to test the viscosity isincreased from 1 rpm to 100 rpm, more desirably for this process theviscosity varies by a factor from 10 to 800, and preferably from 15 or200. The viscosities are measured with a Brookfield cone and plateviscometer, Model DVII, at 25° C.

The polymerization temperature for polymerizing the monomers in thelatex is desirably from 20 or 40 to 110° C., more desirably from 50 to100° C., and preferably from 65 to 95° C.

The above dispersions can be formulated in low shrinkage caulkingformulations, especially waterbased low volatile organic or volatileorganic free formulations. The caulking formulation may includeinorganic fillers such as chalk, talc, titanium dioxide (available inmany forms as a white pigment), zinc oxide and kaolin clays. Thesefillers may be present at concentrations up to 70 wt. % of the solids.The caulking formulation may include various plasticizers such as lowmolecular weight (i.e. less than 10,000; 20,000; or 30,000 weightaverage molecular weight) polymers or oligomers which are compatiblewith the one or more polymers of the polymer dispersion. They serve tosoften the polymer composition. The caulking formulation may includebiocides (such as fungicides and mildewcides), U.V. stabilizers,antioxidants, adhesion promoters, viscosity modifiers (which increase ordecrease viscosity) coalescing agents, and crosslinking agents.Preferably, at least 60, 70, 80, or 90 wt. % of the solids of thecaulking formulation are the polymeric particles of the dispersion.(Note that solids here refer to nonvolatiles components at 105° C. for 1hour.) Desirably the caulking releases less than 25 or 30, preferablyless than 20 or 15 wt. % volatiles, (organic and water) on drying at105° C. for 1 hour. Desirably the caulk has an extrudability by ASTMD2452 at 20 psi with a 0.104" orifice of less than 400 seconds at 25°C., more desirably from 10 to 400 seconds, and preferably from 20 to 100or 200 seconds. The polymer dispersion may have polymers having 2 ormore separate Tg values. Low Tg values are desirable for low temperatureflexibility however they can be tacky at higher temperatures. Byselecting the appropriate monomers for the latex and polymerization twoor more phase separated polymers may be present in the caulk giving twoTg values and both low temperatures flexibility and low tack in oneformulation.

EXAMPLES

Examples 1, 2, 3 and 4 show how the polymer dispersions of thisinvention were prepared at 72, 79, 80, and 87 percent solids.

PROCEDURE:

A 50:50 solution of the deionized water and concentrated ammoniumhydroxide (29-30 wt. % NH₃) was prepared and added dropwise to acarboxylated latex with vigorous stirring to adjust the pH of the latexto about 6.0. The partially neutralized latex was then added to areactor and stirred under nitrogen at 100 rpm. In a typical labpreparation a 4 liter jacketed resin kettle was used as the reactor. Alow speed, high torque electrically powered stirrer equipped with ananchor type blade was used for agitation. The temperature was controlledusing an external heating/cooling bath which circulates a water/glycolmixture through the resin kettle jacket. The latex was heated to 75° C.and a solution of the lauryl mercaptan, t-amyl peroxyneodecanoate, ethylacrylate, and butyl acrylate was added over a 1.5 hour period. The batchtemperature was maintained in the 75-85° C. range throughout theaddition. Fifteen minutes after addition was complete, the t-butylhydroperoxide (1.43 g) was added and cooling was begun. The t-butylhydroperoxide was the first half of the red-ox scavenging system used toreduce the level of unreacted free monomer to an acceptable level. Whenthe batch temperature reached 50° C., a solution of 33.3 wt. % thesodium formaldehyde sulfoxylate, deionized water and 33.3 wt. % anionicsurfactant was added. The sodium formaldehyde sulfoxylate catalyzes thet-butyl hydroperoxide causing it to form free radical containing specieswhich react with any residual free monomer. The batch was stirred for 1hour more at 50° C. during which time the residual monomer was scavenged(consumed), then cooled to room temperature and removed from thereactor. The resultant polymer was very thixotropic. The particle sizedistribution was multimodal. The glass transition temperatures weremeasured using a heating/Perkin Elmer Model D5C7 differential scanningcalorimeter using a heating/cooling rate of 10° C./minute.

The starting latex media for Examples 1, 2, 3 and 4 is a carboxylatedacrylic latex having a solids content of about 66 weight percent and apH of about 2 and a viscosity of about 200 cp. It is commerciallyavailable from The BFGoodrich Company under the tradename Carbobond™ XPD2254.

In a continuous polymerization a heel of previously formed polymer wouldbe added to the reactor and heater to the proper reaction temperatureunder a nitrogen blanket. Both the monomer solution and latex would thenbe pumped into the reactor at an appropriate rate and reacted polymerwould be pumped out of the bottom of the reactor at a rate matching thecombined rate of the latex and monomer addition. This type of reactionscheme would be very similar to a CSTR (continuous stirred tank reactor)set up. A plug flow type reactor could also be used.

                  TABLE I                                                         ______________________________________                                        Example 1                                                                     72.0 Percent Solids Acrylate Polymer                                          REAGENT           WEIGHT (g)                                                                              WEIGHT (%)                                        ______________________________________                                        Latex (67.3% solids)                                                                            4545      84.36                                             Ammonium hydroxide (29-30                                                                       21.5      0.40                                              wt %)                                                                         Deionized water   21.5      0.40                                              Lauryl mercaptan  0.79      0.01                                              t-amyl peroxyneo-decanoate                                                                      3.11      0.06                                              Ethyl Acrylate    390       7.24                                              Butyl Acrylate    390       7.24                                              t-butyl hydroperoxide                                                                           1.43      0.03                                              Sodium Formaldehyde                                                                             2.86      0.05                                              Sulfoxylate                                                                   Deionized Water   8.58      0.16                                              Anionic Surfactant*                                                                             2.86      0.05                                              ______________________________________                                         *ABEX JKB ™ manufactured by RhonePoulenc                              

The final dispersion had a cone and plate viscosity (Brookfield ModelNo. DVII) of 600 cps at 100 rpm (75° F.) and 4,500 cps at 1 rpm (75°F.). The particle size distribution of this dispersion was typicallybimodal with one mode centered at 0.4 to 0.7 microns and another modecentered at 1 to 3 microns. Fully coalesced and dried films of thisdispersion exhibited two glass transition temperatures, one at -21 to-23° C. and one at -30 to -31° characteristic of different acrylatecopolymers. The glass transition temperatures were measured using aPerkin Elmer Model DSC7 differential scanning calorimeter using aheating/cooling rate of 10° C.

                  TABLE II                                                        ______________________________________                                        Example 2                                                                     79.72 Percent Solids Acrylate Polymer                                         REAGENT           WEIGHT (g)                                                                              WEIGHT (%)                                        ______________________________________                                        Latex (67.3% solids)                                                                            4545      60.12                                             Ammonium hydroxide (29-30                                                                       21.5      0.28                                              wt %)                                                                         Deionized water   21.5      0.28                                              Lauryl mercaptan  2.92      0.04                                              t-amyl peroxyneo-decanoate                                                                      11.59     0.15                                              Ethyl Acrylate    1450      19.18                                             Butyl Acrylate    1450      19.18                                             t-butyl hydroperoxide                                                                           5.32      0.07                                              Sodium Formaldehyde                                                                             10.64     0.14                                              Sulfoxylate                                                                   Deionized Water   31.90     0.42                                              Anionic Surfactant*                                                                             10.63     0.14                                              ______________________________________                                         *ABEX JKB                                                                

The final dispersion had a cone and plate viscosity (Brookfield ModelDVII) of 6,000 cps at 100 rpm (75° F.) and 300,000 at 1 rpm (75° F.).Fully coalesced and dried films of this dispersion showed two separateglass transition temperatures as in Example 1. The particle sizedistribution of this dispersion was typically bimodal with one modecentered at 0.4 to 0.7 microns and the second mode centered at 2 to 4microns.

                  TABLE III                                                       ______________________________________                                        Example 3                                                                     87.17 Percent Solids Acrylate Polymer                                         REAGENT           WEIGHT (g)                                                                              WEIGHT (%)                                        ______________________________________                                        Latex (67.3% solids)                                                                            4545      36.26                                             Ammonium hydroxide (29-30                                                                       21.5      0.17                                              wt %)                                                                         Deionized water   21.5      0.17                                              Lauryl mercaptan  7.9       0.06                                              t-amyl peroxyneo-decanoate                                                                      31.2      0.25                                              Ethyl Acrylate    3877      30.92                                             Butyl Acrylate    3877      30.92                                             t-butyl hydroperoxide                                                                           14.3      0.11                                              Sodium Formaldehyde                                                                             28.6      0.23                                              Sulfoxylate                                                                   Deionized Water   85.8      0.68                                              Anionic Surfactant*                                                                             28.6      0.23                                              ______________________________________                                         *ABEX JKB                                                                

The final dispersion has a cone and plate viscosity (Brookfield ModelDVII) of <10,000 cps at 100 rpm (750° F.) and >100,000 at 1 rpm (75°F.). The polymer exhibits good long term storage stability. The polymerwas easily spread into thin films. The particle size distribution ofthis dispersion was typically trimodal with one mode centered at 0.4 to0.7 microns, one mode centered at 2 to 4 microns and a third modecentered at 8 to 30 microns. Fully coalesced and dried films of thisdispersion show two separate glass transition temperatures as inExamples 1 and 2.

A similar latex to Example 3 was made using the same procedure andrecipe but substituting as the starting latex Rhoplex™ 2620(commercially available latex) from Rohm and Haas at 62 weight percentsolids and having a monomer composition similar to Carbobond™. Theresulting polymer dispersion had 85.8 weight percent solids and aviscosity at a pH of 6 similar to Example 3.

Another similar latex to Example 3 was made using the same procedure andrecipe but substituting as the starting latex Acronal V275™ from BASF at65 weight percent solids and having a monomer composition similar toCarbobondTM plus a few weight percent acrylonitrile. The resultingpolymer dispersion had 86.5 weight percent solids and a viscosity at apH of 6 similar to Example 3.

Example 4

An example of a polymerization using only butyl acrylate in the secondadded monomer is shown in Table IV. This polymerization used the samestarting latex as in examples 1, 2 and 3. Also, the same procedure wasused as in Examples 1, 2 and 3.

                  TABLE IV                                                        ______________________________________                                        Example 4                                                                     79% Solids Acrylate Polymer                                                   REAGENT           WEIGHT (g)                                                                              WEIGHT (%)                                        ______________________________________                                        Latex (67.3% solids)                                                                            4545      61.38                                             Ammonium hydroxide (29-30                                                                       21.5      0.29                                              wt %)                                                                         Deionized water   21.5      0.29                                              Lauryl mercaptan  2.9       0.04                                              t-amyl peroxyneo-decanoate                                                                      11.6      0.16                                              Butyl Acrylate    2744      37.06                                             t-butyl hydroperoxide                                                                           10.6      0.07                                              Sodium Formaldehyde                                                                             32.0      0.14                                              Sulfoxylate                                                                   Deionized Water   32.0      0.43                                              Anionic Surfactant*                                                                             10.6      0.14                                              ______________________________________                                         *ABEX JKB                                                                

The final dispersion had a cone and plate viscosity (Brookfield ModelDVII) of 6,100 cps at 100 rpm (75° F.) and 70,000 cps at 1 rpm (75° F.).The particle size distribution of the dispersion was typically trimodalwith one mode centered at 0.4 to 0.7 microns, another mode centered at 2to 4 microns and a third mode centered at 8 to 30 microns. Fullycoalesced and dried films of this dispersion show two separate glasstransition temperatures, one at -21 to -23° C. which is characteristicof the starting latex and another at -45 to -53° C. which ischaracteristic of polybutyl acrylate. The glass transition temperatureswere measured using a Perkin Elmer Model DSC7 differential scanningcalorimeter using a heating/cooling rate of 10° C./minute. Dried filmsof this dispersion exhibit both the low temperature flexibility expectedof a material such as polybutylacrylate with a Tg of -45 to -53° C. aswell as the lower tack surface associated with a higher Tg polymer suchas the starting latex.

Examnple 5

An example of a polymerization using a vinyl acetate type starting latexis illustrated in Table V. The procedure for making this polymer wasidentical to that used for an acrylic starting latex. The latex used inthis example is a commercially available ethylene vinyl acetate latexmanufactured by Air Products, Inc. The latex has a trade name ofAirflex® 500. This latex had a solids content of 55% by weight, a pH of4.9 as received and a Tg of 5° C.

                  TABLE V                                                         ______________________________________                                        82.3 Percent Solids Vinyl Acetate - Acrylate Polymer                          REAGENT              WEIGHT (g)                                               ______________________________________                                        Airflex ® 500 (pH adjusted to 5.6)                                                             4550                                                     (vinyl acetate latex)                                                         Lauryl Mercaptan     7.3                                                      Ethyl Acrylate       3750                                                     Butyl Acrylate       3750                                                     T-Amyl Peroxy Neodecanoate                                                                         22.8                                                     T-Butyl Hydroperoxide                                                                              14.3                                                     Sodium Formaldehyde Sulfoxylate                                                                    28.6                                                     Anionic Surfactant/Deionized water                                                                 120                                                      (1 part surfactant/4 parts water)                                             ______________________________________                                    

The final dispersion had a solids content of 82.3% by weight. Thisdispersion had a cone and plate viscosity (Brookfield Model No. DVII) ofless than 20,000 cps at 50 rpm (75° F.) and less than 1,000,000 cps at 1rpm (75° F.).

Example 6

The micrographs of FIG. 1 show a series of wet polymer dispersionsprepared similarly to Examples 1-4 that have been sandwiched between twomicroscope slides. These polymers were not diluted. These micrographsshow the range in particle size distribution and morphology that can beachieved in the pH and solids range shown by samples A-K in thefollowing Table VI.

                  TABLE VI                                                        ______________________________________                                                                  WEIGHT PERCENT                                      SAMPLE             pH     SOLIDS                                              ______________________________________                                        A       61          5.95  85.5                                                B       64          5.95  88.0                                                C       66         6.8    88.0                                                D       67         5.1    83.0                                                E       68          5.95  85.5                                                F       69         5.1    88.0                                                G       70          5.95  88.0                                                H       71         5.1    85.5                                                I       72         5.1    88.0                                                J       73         6.8    83.0                                                K       74         5.1    85.5                                                ______________________________________                                    

Example 7

A typical sealant formulation using a dispersion of polymer particles ofthis disclosure is shown below:

                  TABLE XVII                                                      ______________________________________                                                       WEIGHT IN                                                      INGREDIENT     FORMULATION  WEIGHT (%)                                        ______________________________________                                        Polymer Particle Dispersion                                                                  2500 g       93.04                                             (85% Solids)                                                                  Fungicide      2.5 g        0.09                                              Ethylene Glycol                                                                              27.0 g       1.00                                              Propylene Glycol                                                                             27.0 g       1.00                                              Mineral Oil    116.0 g      4.32                                              Epoxy Silane   9.4 g        0.35                                              Mildewcide     5.0 g        0.19                                              ______________________________________                                    

The sealant was formulated using a planetary mixer having a workingcapacity of about 3/4 gallons, and capable of handling viscous,thixotropic materials and having vacuum mixing capability. The mixer hadvariable mixing speeds from 40 to 200 rpm. The dispersion of polymerparticles, fungicide and glycols was added to the mixer and mixed untiluniform, usually from 5-10 minutes. The mineral oil, epoxy silane andmildewcide were then added and mixed until uniform. The pH of the batchwas then adjusted by adding a mixture of 50/50 concentratedammonia/deionized water to the desired final batch pH, which wastypically between 6.5 to 8.0. The material was then mixed with vacuumfor 20 minutes to remove any air from the sealant. The material was thenpackaged into cartridges.

Example 8

Several examples from U.S. Pat. No. 4,130,523 ('523) were prepared tocompare the viscosity values generated at different solids contents tothe viscosities generated by the method of this disclosure. Theviscosities are shown below.

                  TABLE XVIII                                                     ______________________________________                                                                 Method of                                                                            Method of                                                                             Method of                                    '523              this   this    this                                  Wt. %  Ex. 1    '523     Disclosure                                                                           Disclosure                                                                            Disclosure                            Solids pH = 6.4 Ex. 2    pH = 6.0                                                                             pH = 6.0                                                                              pH = 9                                ______________________________________                                        52                       52                                                   57     1,000             55                                                          cps                                                                      58.6                                   59                                   62                       79                                                   63     5,000                                                                         cps                                                                      63.9           1,460                                                        67                       118    241                                             68.4 11,000                           444                                   72              18,000   314                                                  77                       750                                                  82                       12,700                                                 85.5                   50,000                                               ______________________________________                                         Viscosities @ 24° C., 20 rpm with a cone and plate viscometer.    

The dispersion of polymer particles is useful as a source of bulkpolymer or as an alternative to a conventional latex. It may be used formolding or forming operations, as a thixotropic material for flexible orrigid membranes or in coatings or in sealants. A formulated sealant fromthe dispersion of polymer particles is useful as a thixotropic materialfor flexible or rigid membranes or coatings, or as a thixotropic sealantor caulk. The caulk is useful in residential or commercial constructionor maintenance. It functions to seal interstices either in a structuralmaterial or between two or more structural materials or functions tofill expansion joints in concrete or other building structures.

The caulking compounds and sealants according to the invention may begunned or extruded or otherwise formed into various profiles withconventional equipment such as caulking guns and caulking tubes. Theycan be formulated desirably to have volume shrinkage values from about 5to 30%, and more desirably from 8 to 20%.

These caulking compounds have lower shrinkage, high elongation, lowmodulus, good adherence to a variety of substrates, and a fast dry to alow tack surface. They are non-staining and form a dried caulk that iseasily coated with traditional latex or oil-based commercial coatings.

The high solids polymer dispersions of this invention are also useful toformulate adhesives. The inherent low viscosity of these high solidspolymer dispersions at high polymer solids contents makes themparticularly useful in formulating high solids, low VOC, water borneadhesives. Also, the broad particle size distribution of thesedispersions make them well suited to certain pressure sensitive adhesiveapplications such as respositionable adhesives. Optionally, variousadditives such as diluents and tackifiers may be added to reduce theviscosity of the wet adhesive or increase the tack of dried adhesivefilms. The adhesive comprises about 0.1 to about 9.5 parts water and Ipart high solids polymer dispersion, preferably about 0.33 to about 3parts water and about 1 parts high solids polymer dispersion, morepreferably about 0.5 to 2 parts water and 1 part high solids polymerdispersion. Preferably, the viscosity of the resulting adhesive is about10 to 10,000 cps, more preferably, about 100 to 2,000 cps. Viscosity ismeasured at 75° C. using a Brookfield Model DVII cone and plateviscometer at 20 rpm.

These adhesives are applied by conventional techniques such as byroller, brush or spray to a substrate, to provide an adhesive filmhaving a thickness of from about 5 to 200 μm, preferably from about 7 to40 μm, more preferably from about 10 to 30 μm. Typical substrates towhich these adhesives can be applied include, for example, paper, metalfoil and polymer films such as polyester film. The adhesives are driedunder ambient conditions or at elevated temperatures to provide driedadhesive films, preferably having less than about 5 wt. % water. Thedried adhesive films are useful as repositionable pressure sensitiveadhesives; and are useful to make self adhering repositionablematerials.

Example 9

An adhesive as described above was formulated using the dispersion ofExample 2. One part water was added to three parts high solids polymerdispersion to provide an adhesive. The adhesive had a viscosity of 35cps measured at 75° F. using a Brookfield Model DVII cone and plateviscometer at 20 rpm. The adhesive was applied to a sheet of 20 lb stockpaper by brush, then allowed to dry at ambient temperature for 30minutes, and the dried at 120° F. for one hour to provide an adhesivefilm. The dried adhesive film had a coverage of 15-30 g/m². A secondsheet of 20 lb stock paper was placed on the dried adhesive film andpressure was applied to the paper. The second sheet of paper adheredsatisfactorily to the dried adhesive film and the two sheets of paperremained affixed.

Examnple 10

An adhesive was formulated using the high solid polymer dispersion ofExample 2. One part water was added to one part high solids polymerdispersion to provide an adhesive. The adhesive had a viscosity of 10cps measured at 75° F. using a Brookfield Model DVII cone and plateviscometer at 20 rpm. The adhesive was applied by brush to a sheet of 20lb stock paper, then allowed to dry at ambient temperature for 30minutes, and then dried at 120° F. for one hour to provide an adhesivefilm. The dried adhesive film had a coverage of 40-60 g/m². A secondsheet of 20 lb stock paper was placed on the dried adhesive film andpressure was applied to the paper. The second sheet of paper adheredsatisfactorily to the dried adhesive film and the two sheets of paperremained affixed.

While in accordance with the Patent Statutes, the best mode andpreferred embodiment has been set forth, the scope of the invention isnot limited thereto, but rather by the scope of the attached claims.

What is claimed is:
 1. A caulking or sealant composition comprising:a) apolymeric dispersion which is at least 75 wt. % polymer particles in amedium comprising water, wherein the polymer particles have a particlesize distribution having particles of diameter of 4.0 microns or more,and wherein the particles of diameter of 4.0 microns or more havenonspherical shape such that they have an average aspect ratio betweenlargest and smallest diameter of each particle of at least 1.5, andwherein said particles of said dispersion are comprised of at least 50wt. % repeat units from one or more acrylate and/or vinyl acetatemonomers.
 2. The caulking or sealant composition according to claim 1,wherein the polymer particles are at least 80 wt. % of said polymericdispersions, wherein the particles of diameters of 4.0 microns or moreare at least 30 wt. % of said polymeric dispersion and wherein saiddispersion includes at least 10 wt. % particles of diameters of lessthan 4 microns.
 3. The caulking or sealant composition according toclaim 2, wherein the extrudability of said composition by ASTM D2452 at20 psi with a 0.104" orifice is less than 400 seconds at 25° C.
 4. Thecaulking or sealant composition according to claim 3, wherein saidpolymer particles are at least 70 wt. % acrylate repeat units fromacrylate monomers of the structure ##STR1## where R₁ is H or CH₃ and R₂is an alkyl of 1 to 13 carbon atoms.
 5. A caulking or sealantcomposition comprising:an aqueous dispersion being at least 75 wt. %discrete polymer particles polymerized from monomers being at least 50wt. % of one or more acrylate monomers having from 4 to 16 carbon atomsand/or vinyl acetate, said dispersion having a particle sizedistribution, said particle size distribution having at least one modein the particle size distribution between 0.05 μm and 0.7 μm and atleast another mode between 0.7 μm and 100 μm, and wherein the particlesize distribution has at least 20 wt. % of particles greater than 1 μmin diameter.
 6. The caulking or sealant composition according to claim5, wherein said composition includes a mildewcide or fungicide and ispackaged in cartridges.
 7. The caulking or sealant composition accordingto claim 6, wherein said composition further comprises mineral oil. 8.The caulking or sealant composition according to claim 1, wherein saidcomposition further comprises ethylene glycol or propylene glycol ormixtures thereof.
 9. The caulking or sealant composition according toclaim 7, wherein said composition further comprises ethylene glycol orpropylene glycol or mixtures thereof.
 10. A caulking or sealantcomposition according to claim 5, wherein said particle sizedistribution has at least one mode between 0.7 and 4 μm diameter, and atleast one mode between 4 and 100 μm diameter, and wherein said particlesize distribution has at least 20 wt. % of particles above 1 μm indiameter and at least 15 weight % of particles above 4 μm in diameter.11. An adhesive composition comprising:a. one part of a high solidsdispersion of polymer particles, said polymer dispersion comprising anaqueous dispersion being at least 77 wt. % discrete polymer particlespolymerized from monomers comprising at least 50 wt. % acrylate monomershaving 4 to 16 carbon atoms and/or vinyl acetate, said dispersion havinga particle size distribution comprising a first mode and a second mode,wherein said first and second modes are selected from the groupconsisting of: a first mode having particles of diameter between 0.05 μmto 4 μm and a second mode having particles of diameter between above 4μm to 100 μm; a first mode having particles of diameter between 0.05 μmand 0.7 μm and a second mode having particles of diameter between above0.7 μm and 100 μm; and a first mode having particles of diameter lessthan 1 μm and said second mode having particles of diameter greater than1 μm; and b. from about 0.1 to about 9.5 parts of water.
 12. Theadhesive composition according to claim 11, wherein the first mode hasparticles of diameters from about 0.05 μm to 4 μm and the second modehas particles of diameters from above about 4 μm to 100 μm.
 13. Theadhesive composition according to claim 11, wherein the first mode hasparticles of diameters between about 0.05 μm and 0.7 μm and the secondmode has particles of diameters from about 0.7 μm to 100 μm, and whereinsaid particle size distribution has at least 20 weight percent ofparticles greater than about 1 μm in diameter.
 14. The adhesivecomposition according to claim 11, wherein the first mode has particlesof diameters less than 1 μm and the second mode has particles ofdiameters greater than 1 μm, and wherein said high solids polymerdispersion comprises at least 80 wt. % discrete polymer particlespolymerized from unsaturated monomers comprising at least 50 wt. %acrylate monomers having 4 to 16 carbon atoms and/or vinyl acetate. 15.The adhesive composition according to claim 11, wherein the peak of thefirst mode is centered at particles of diameters from about 0.4 μm to0.7 μm and the peak of the second mode is centered at particles ofdiameters from about 2 μm to 4 μm, and wherein said high solids polymerdispersion comprises at least 79 wt. % discrete polymer particlespolymerized from unsaturated monomers comprising at least 50 wt. %acrylate monomers having 4 to 16 carbon atoms and/or vinyl acetate. 16.A method for adhering one substrate to another comprising the stepsof:a. providing an adhesive, said adhesive comprising one part of a highsolids dispersion of polymer particles, said polymer dispersioncomprising an aqueous dispersion being at least 77 wt. % discretepolymer particles polymerized from monomers comprising at least 50 wt. %acrylate monomers having 4 to 16 carbon atoms and/or vinyl acetate, saiddispersion having a particle size distribution comprising a first modeand a second mode, wherein said first and second modes are selected fromthe group consisting of: a first mode having particles of diameterbetween 0.05 μm to 4 μm and a second mode having particles of diameterbetween above 4 μm to 100 μm; a first mode having particles of diameterbetween 0.05 μm and 0.7 μm and a second mode having particles ofdiameter between above 0.7 μm and 100 μm; and a first mode havingparticles of diameter less than 1 μm and a second mode having particlesof diameter greater than 1 μm; and from about 0.1 to about 9.5 parts ofwater; b. providing a first substrate, said first substrate having anapplication surface; c. providing a second substrate, said secondsubstrate having an attachment surface; d. applying said adhesive tosaid application surface of said first substrate; e. then drying saidadhesive; and f. then positioning said attachment surface of said secondsubstrate on the dried adhesive.
 17. The method according to claim 16,wherein the first mode has particles of diameters from about 0.05 μm to4 μm and the second mode has particles of diameters from above about 4μm to 100 μm.
 18. The method according to claim 16, wherein the firstmode has particles of diameters between about 0.05 μm to 0.7 μm and thesecond mode has particles of diameters from about 0.7 μm to 100 μm, andwherein said particle size distribution has at least 20 weight percentof particles greater than about 1 μm in diameter.
 19. The methodaccording to claim 16, wherein the first mode has particles of diametersless than 1 μm and the second mode has particles of diameters greaterthan 1 μm, and wherein, said high solids polymer dispersion comprises atleast 80 weight percent discrete polymer particles polymerized fromunsaturated monomers comprising at least 50 weight percent acrylatemonomers having 4 to 16 carbon atoms and/or vinyl acetate.
 20. Themethod of claims 16 further comprising the step of applying pressure tosaid second substrate or said first substrate after step f.
 21. Themethod of claim 16 wherein said first substrate and said secondsubstrate comprise paper.
 22. A self-adhering repositionable materialcomprising:a. a substrate; b. a dried adhesive film disposed on saidsubstrate, said dried adhesive film comprising discrete polymerparticles polymerized from monomers comprising at least 50 wt. %acrylate monomers having 4 to 16 carbon atoms and/or vinyl acetate, saidpolymer particles having a particle size distribution comprising a firstmode and a second mode, wherein said first and second modes are selectedfrom the group consisting of: a first mode having particles of diameterbetween 0.05 μm to 4 μm and a second mode having particles of diameterbetween above 4 μm to 100 μm; a first mode having particles of diameterbetween 0.05 μm and 0.7 μm and a second mode having particles ofdiameter between above 0.7 μm and 100 μm; and a first mode havingparticles of diameter less than 1 μm and a second mode having particlesof diameter greater than 1 μm.
 23. The self adhering repositionablematerial according to claim 22, wherein the first mode has particles ofdiameters from about 0.05 μm to 4 μm and the second mode has particlesof diameters from above about 4 μm to 100 μm.
 24. The self adheringrepositionable material according to claim 22, wherein the first modehas particles of diameters between about 0.05 μm to 0.7 μm and thesecond mode has particles of diameters from about 0.7 μm to 100 μm, andwherein said particle size distribution has at least 20 weight percentof particles greater than about 1 μm in diameter.
 25. The self adheringrepositionable material according to claim 22, wherein the first modehas particles of diameters less than 1 μm and the second mode hasparticles of diameters greater than 1 μm, and wherein said high solidspolymer dispersion comprises at least 80 weight percent discrete polymerparticles polymerized from unsaturated monomers comprising at least 50weight percent acrylate monomers having 4 to 16 carbon atoms and/orvinyl acetate.
 26. The self adhering repositionable material accordingto claim 22, wherein said substrate comprises paper.
 27. The selfadhering repositionable material according to claim 22, wherein saiddried adhesive film contains less than about 5 wt. % water.